vcan.c revision 3ccd4c6167d3b39d52631767ebbf8b5677c5855d
1/* 2 * vcan.c - Virtual CAN interface 3 * 4 * Copyright (c) 2002-2007 Volkswagen Group Electronic Research 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of Volkswagen nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * Alternatively, provided that this notice is retained in full, this 20 * software may be distributed under the terms of the GNU General 21 * Public License ("GPL") version 2, in which case the provisions of the 22 * GPL apply INSTEAD OF those given above. 23 * 24 * The provided data structures and external interfaces from this code 25 * are not restricted to be used by modules with a GPL compatible license. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 30 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 31 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 32 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 33 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 37 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 38 * DAMAGE. 39 * 40 * Send feedback to <socketcan-users@lists.berlios.de> 41 * 42 */ 43 44#include <linux/module.h> 45#include <linux/init.h> 46#include <linux/netdevice.h> 47#include <linux/if_arp.h> 48#include <linux/if_ether.h> 49#include <linux/can.h> 50#include <linux/can/dev.h> 51#include <net/rtnetlink.h> 52 53static __initdata const char banner[] = 54 KERN_INFO "vcan: Virtual CAN interface driver\n"; 55 56MODULE_DESCRIPTION("virtual CAN interface"); 57MODULE_LICENSE("Dual BSD/GPL"); 58MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>"); 59 60 61/* 62 * CAN test feature: 63 * Enable the echo on driver level for testing the CAN core echo modes. 64 * See Documentation/networking/can.txt for details. 65 */ 66 67static int echo; /* echo testing. Default: 0 (Off) */ 68module_param(echo, bool, S_IRUGO); 69MODULE_PARM_DESC(echo, "Echo sent frames (for testing). Default: 0 (Off)"); 70 71 72static void vcan_rx(struct sk_buff *skb, struct net_device *dev) 73{ 74 struct can_frame *cf = (struct can_frame *)skb->data; 75 struct net_device_stats *stats = &dev->stats; 76 77 stats->rx_packets++; 78 stats->rx_bytes += cf->can_dlc; 79 80 skb->protocol = htons(ETH_P_CAN); 81 skb->pkt_type = PACKET_BROADCAST; 82 skb->dev = dev; 83 skb->ip_summed = CHECKSUM_UNNECESSARY; 84 85 netif_rx_ni(skb); 86} 87 88static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev) 89{ 90 struct can_frame *cf = (struct can_frame *)skb->data; 91 struct net_device_stats *stats = &dev->stats; 92 int loop; 93 94 if (can_dropped_invalid_skb(dev, skb)) 95 return NETDEV_TX_OK; 96 97 stats->tx_packets++; 98 stats->tx_bytes += cf->can_dlc; 99 100 /* set flag whether this packet has to be looped back */ 101 loop = skb->pkt_type == PACKET_LOOPBACK; 102 103 if (!echo) { 104 /* no echo handling available inside this driver */ 105 106 if (loop) { 107 /* 108 * only count the packets here, because the 109 * CAN core already did the echo for us 110 */ 111 stats->rx_packets++; 112 stats->rx_bytes += cf->can_dlc; 113 } 114 kfree_skb(skb); 115 return NETDEV_TX_OK; 116 } 117 118 /* perform standard echo handling for CAN network interfaces */ 119 120 if (loop) { 121 struct sock *srcsk = skb->sk; 122 123 skb = skb_share_check(skb, GFP_ATOMIC); 124 if (!skb) 125 return NETDEV_TX_OK; 126 127 /* receive with packet counting */ 128 skb->sk = srcsk; 129 vcan_rx(skb, dev); 130 } else { 131 /* no looped packets => no counting */ 132 kfree_skb(skb); 133 } 134 return NETDEV_TX_OK; 135} 136 137static const struct net_device_ops vcan_netdev_ops = { 138 .ndo_start_xmit = vcan_tx, 139}; 140 141static void vcan_setup(struct net_device *dev) 142{ 143 dev->type = ARPHRD_CAN; 144 dev->mtu = sizeof(struct can_frame); 145 dev->hard_header_len = 0; 146 dev->addr_len = 0; 147 dev->tx_queue_len = 0; 148 dev->flags = IFF_NOARP; 149 150 /* set flags according to driver capabilities */ 151 if (echo) 152 dev->flags |= IFF_ECHO; 153 154 dev->netdev_ops = &vcan_netdev_ops; 155 dev->destructor = free_netdev; 156} 157 158static struct rtnl_link_ops vcan_link_ops __read_mostly = { 159 .kind = "vcan", 160 .setup = vcan_setup, 161}; 162 163static __init int vcan_init_module(void) 164{ 165 printk(banner); 166 167 if (echo) 168 printk(KERN_INFO "vcan: enabled echo on driver level.\n"); 169 170 return rtnl_link_register(&vcan_link_ops); 171} 172 173static __exit void vcan_cleanup_module(void) 174{ 175 rtnl_link_unregister(&vcan_link_ops); 176} 177 178module_init(vcan_init_module); 179module_exit(vcan_cleanup_module); 180